The primary goal of the Trace Element Analysis (TEA) Core (Core B) is to provide specific analytical services and method development to the Dartmouth SBRP researchers in order for them to successfully complete the aims of their research projects. Toward that end this core is committed to providing the highest quality expertise, services and instrumentation for its investigators. The services provided include the routine determination of trace elements, especially arsenic and mercury, by ICPMS methodologies in many different environmental and human samples. More specialized analytical techniques, like elemental speciation and isotope ratio determinations, are also offered and it is proposed to further develop and expand the elemental speciation capabilities (e.g., arsenic speciation of human samples like urine, hair and nails). Instrumentation has been added to the Core to facilitate speciation of methylmercury and inorganic mercury in small zooplankton samples, an application we propose to further develop in order to be able to provide robust and reliable determinations of methylmercury and methylmercury to inorganic mercury ratios at a picogram level in sub mg zooplankton samples. In addition to the services and instrumentation that support the SBRP program, a key resource of this core is extensive experience of its professional staff in analytical chemistry, trace element determinations, and the development of new analytical instrumentation and methodologies. The resources and experience of the Trace Element Analysis core is of immense value to the overall program by catalyzing new interdisciplinary collaborations through novel application of its analytical chemistry capabilities and maintaining an ongoing dialogue with the researchers of the Dartmouth SBRP program.